ABIM - Supraventricular & Ventricular Arrhythmias

Here are key facts for American Board of Internal Medicine from the Arrhythmias tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. Atrial Flutter ECG features: Rapid, regular P waves give ECG "sawtooth" appearance. Atria beat ~300 beats/minute. Only ½ - 1/3 of the electrical impulses make it through the AV node and reach the ventricles, so heart rate is increased ~150 beats per minute. 2. Atrial Fibrillation ECG features: Rapid, irregular and indiscrete P waves on ECG. Atria do not contract in coordinated fashion, but send fast and irregular signals to ventricles increase heart rate. 3. Atrial arrhythmia management: Rate control with beta-blockers, calcium channel blockers (verapamil, diltiazem). Rhythm control with cardioversion, drugs (antiarrhythmics), possibly ablation. Anticoagulants (warfarin) are used to prevent thromboembolism. 1. WPW diagnostic features: Short PR interval and positive delta wave at beginning of broad QRS complex; delta wave reflects early depolarization. Occurs as result of AV node bypass, called bundle of Kent. 2. WPW management: Direct-current cardioversion therapy is preferred; long term treatment may require catheter ablation. 3. Critical medication contraindication: Beware digoxin/nondihydropyridine calcium channel blockers to WPW patients, as they may trigger ventricular fibrillation (fatal). 1. Ventricular tachycardia definition: 3+ consecutive beats 120+ beats/minute; abnormal ventricular automacy. 2. Torsades de Pointes identification: Rapid, irregular QRS complexes "spiral" around baseline, as ventricular rate varies from cycle to cycle. Special case of ventricular tachycardia, associated with Long QT Syndrome. 3. Ventricular arrhythmia management: Cardioversion, antiarrhythmic drugs, defibrillator implant for VT; Magnesium for Torsades; CPR & Defibrillation for ventricular fibrillation.

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1. Atrial Flutter symptoms: May be none. Or, may cause palpitations, and reduced CO, difficulty breathing, weakness, chest discomfort, syncope. 2. Atrial Fibrillation symptoms: May be asymptomatic. Or, may experience lack of energy, fast, irregular pulse, difficulty breathing, palpitations, chest discomfort, dizziness. 3. WPW presentation: May be asymptomatic. May have episodes of increased heart rate, chest pain, dizziness, palpitations, difficulty breathing. 4. Ventricular tachycardia symptoms: May be asymptomatic if duration is short (aka, paroxysmal) or rate is not excessive; If sustained, palpitations, difficulty breathing, chest pain, dizziness, fainting, death. 1. Atrial Flutter risks: Commonly occurs in healthy people, but risk increases with other cardiac conditions, binge alcohol consumption, diabetes. 2. Atrial Fibrillation risks: Other cardiac problems, hyperthyroidism, obesity, diabetes, lung disease, binge alcohol consumption. 3. Premature beats triggers: Stress, caffeine, alcohol, hypoxia, electrolyte imbalances. Heart disease, pulmonary disease, and scarring can also interfere with normal electrical activity. 4. Ventricular arrhythmia risks: Heart disease, electrolyte imbalances, medications. 1. Atrial Fibrillation workup: Echocardiography to check for structural defects, thyroid function tests. Must rule out Wolff-Parkinson-White Syndrome before prescribing AV-node blocking drugs. 2. Long QT identification: Long QT interval on ECG, reflects defective ion channels. 3. Long QT types: Romano-Ward Syndrome (Types 1-3) and Jervell and Lange-Nielsen Syndrome, which is also associated with congenital deafness. 4. Torsades triggers: Electrolyte imbalances (hypocalcemia, hypokalemia); Medications (antiarrhythmics, tricyclic antidepressants, anti-histamines when taken with erythromycin). 1. Atrial Flutter complications: When coupled with other cardiac complications, can lead to stroke, makes heart work more difficult, ventricular weakening, and coagulation is more likely. Patients may have periods of atrial fibrillation. 2. Atrial Fibrillation concerns: Stroke, systemic emboli. 3. WPW associated conditions: Associated with Ebstein anomaly, displaced tricuspid valve. Atrial fibrillation can develop (depends on presence of antegrade conduction through accessory connection). 4. Progression risks: Premature beats can develop flutter/fibrillation. Ventricular tachycardia can lead to heart failure, unconsciousness, sudden death by cardiac arrest. Torsades can lead to ventricular fibrillation, which is fatal.

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Below is information not explicitly contained within the tutorial but important for ABIM. 1. Rate vs. rhythm control: Major clinical trials comparing strategies and outcomes for atrial fibrillation management. 2. Anticoagulation risk-benefit: Application of CHA₂DS₂-VASc and HAS-BLED scores in clinical decision making. 3. Catheter ablation efficacy: Current evidence for ablation in various arrhythmias and patient populations. 4. ICD primary prevention: Risk stratification for sudden cardiac death and device therapy indications. 1. Elderly patients: Modifications to diagnosis and treatment approaches in geriatric populations. 2. Heart failure with arrhythmias: Intersection of heart failure management and arrhythmia treatment. 3. Renal dysfunction: Medication adjustments and procedural considerations in patients with kidney disease. 4. Pregnancy: Management approaches for arrhythmias during pregnancy. 1. Antiarrhythmic selection: Factors influencing choice of specific agents based on efficacy, safety, and comorbidities. 2. Anticoagulant transitions: Managing perioperative or procedure-related interruptions in anticoagulation. 3. QT-prolonging drug interactions: Recognition and management of drug combinations that increase arrhythmia risk. 4. Rate control optimization: Strategies for achieving adequate rate control while minimizing side effects. 1. Left atrial appendage closure: Role as an alternative to anticoagulation in selected patients. 2. Subcutaneous ICDs: Indications and limitations compared to traditional transvenous devices. 3. Leadless pacemakers: Current technology and appropriate patient selection. 4. Post-ablation monitoring: Strategies for surveillance after ablation procedures.